How to get edges and normal map from 3D model?
Ref: https://docs.blender.org/manual/en/latest/render/blender_render/textures/properties/influence/bump_normal.html#bump-normal-maps

Normal maps in Blender store a normal as follows:

Red maps from (0 - 255) to X (-1.0 - 1.0)
Green maps from (0 - 255) to Y (-1.0 - 1.0)
Blue maps from (0 - 255) to Z (0.0 - 1.0)

Since normals all point towards a viewer, negative Z values are not stored (they would be invisible anyway). In Blender we store a full blue range, although some other implementations also map blue colors (128 - 255) to (0.0 - 1.0). The latter convention is used in “Doom 3” for example.

If you want to achieve the default Blender normal map definition (z start from 0.0 instead of -1.0). You need to defined what will happen if -1 &lt; z &lt; 0
Below is two examples for how to calculate it by node editor:


Is the first one you are asking for?